Steve is no stranger to heavy bikes.
I met him on the Heart of England 300 in 2011 and he was riding a mountain bike with panniers [this was all in preparation for PBP 2011 which he did on the same set up, if memory is correct].
Commenting on the weight, he said that his fixed wheel bike weighed more than the mountain bike! And he'd been riding that all over the UK past few years without too much trouble.
Also - terrain, roads and weather. Without a support vehicle [which I really don't believe he's at a disadvantage not having, I really don't], he needed something durable that would cope with the conditions here during these first few months.
It's obvious now, that he's prepared really well, put a lot of thought into what will work best for him, both equipment and the way to ride. It's been interesting to here tales of "you'd be surprised how slowly he climbs" from people here.
I remember one time on the Elenith on that big climb after Tregaron, he came waltzing past me on his fixed wheel, out of the saddle pumping hard, like he was on a magic carpet. It's different this time - he's just sitting there right in that all important zone, never pushing too hard, just building up the foundations to increase mileage a bit later. Really fascinating to watch it all unfold.